A quantum mechanical study on the formation of PCDD/Fs from 2-chlorophenol as precursor.
The most direct route to the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in combustion and thermal processes is the gas-phase reaction of chemical precursors such as chlorinated phenols. Detailed insight into the mechanism and kinetics properties is a prerequisite for understanding the formation of PCDD/Fs. In this paper, we carried out molecular orbital theory calculations for the homogeneous gas-phase formation of PCDD/Fs from 2-chlorophenol (2-CP). The profiles of the potential energy surface were constructed, and the possible formation pathways are discussed. The single-point energy calculation was carried out at the MPWB1K/ 6-311+G(3f,2p) level. Several energetically favorable formation pathways were revealed for the first time. The rate constants of crucial elementary steps were deduced over a wide temperature range of 600 approximately 1200 K using canonical variational transition-state theory (CVT) with small curvature tunneling contribution (SCT). The rate-temperature formulas were fitted. The ratio of PCDD to PCDF formed shows strong dependency on the reaction temperature and chlorophenoxy radicals (CPRs) concentration.
Zhang
Qingzhu
Q
Environment Research Institute, Shandong University, Jinan 250100, PR China. zqz@sdu.edu.cn
Li
Shanqing
S
Qu
Xiaohui
X
Shi
Xiangyan
X
Wang
Wenxing
W
D001572:Benzofurans / Q000138:chemical synthesis* / Q000737:chemistry; D002733:Chlorophenols / Q000737:chemistry*; D019281:Dimerization; D007700:Kinetics; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D011789:Quantum Theory; D013696:Temperature
D001572:Benzofurans; D002733:Chlorophenols; D000072317:Polychlorinated Dibenzodioxins; C023614:dibenzofuran